The present invention relates to a pigment yellow 74 and a printing ink composition using it. More specifically, it relates to a pigment yellow 74 improved in color strength and transparency and a printing ink composition using it.
Conventionally, as a yellow pigment for a printing ink, there has been used a disazo yellow pigment using 3,3xe2x80x2-dichlorobenzidine as a tetrazo component and an acetoacetoanilide compound as a coupling component. However, since the disazo yellow pigment has a biphenyl skeleton in its structure and contains chlorine, there is an apprehension of the generation of a toxic material at the time of disposing of a printed matter.
For this reason, it is strongly required to develop a yellow pigment which has pigment performance equivalent to that of the disazo yellow pigment and is producible at a low production cost and excellent in hygiene. Pigment yellow 74 using 2-methoxy-4-nitroaniline as a diazo component and 2-methoxyacetoacetoanilide as a coupling component has advantages of excellent light resistance and clearness but has disadvantages of extremely poor transparency and color strength.
For improving the transparency and color strength of the pigment yellow 74, a surface-treatment technique is conventionally adopted. This technique is a method in which a rosin alkali salt solution (so-called rosin soap) is added into a coupler component or into a pigment slurry after coupling and then a metal salt for a lake such as aluminium sulfate is added to deposit the rosin, as an insoluble rosin lake metal salt, on a pigment surface, whereby a pigment particle shape is finely controlled. However, this technique is not sufficient.
Under the present situation, for the above reason, the pigment yellow 74 is only partially used for a building material coating composition, etc., which is required to have hiding power, and its applications to a printing ink which is required to have higher transparency and color strength have been hardly developed.
It is an object of the present invention to provide a pigment yellow 74 which is improved in transparency and color strength without impairing its inherent light resistance and clearness.
According to the present invention, there is provided a pigment yellow 74 obtained by coupling a coupler component containing 2-methoxyacetoacetoanilide and an acetoacetoanilide derivative of the following formula (1) in an amount of 0.1 to 10 mol %, based on the 2-methoxyacetoacetoanilide, and a diazo component obtained by diazotizing 2-methoxy-4-nitroaniline, 
wherein X may be the same or different and is CONR1R2, SO2NR1R2, NHCOR1, CONH(CH2)KNR1R2 or SO2NH(CH2)KNR1R2 (in which each of R1 and R2 is independently a hydrogen atom or an alkyl group, or R1 and R2 together form a cyclic structure, and k is an integer of 1 to 4), m is 1 or 2, Y may be the same or different and is R3, OR3 (in which R3 is a hydrogen atom or an alkyl group), COOH or SO3H, and n is an integer of 0 to 2.
According to the present invention, further, there is provided a pigment yellow 74 according to the above, wherein the diazo component is obtained by diazotizing the 2-methoxy-4-nitroaniline and an aniline derivative of the following formula (2) in an amount of 0.1 to 10 mol % based on the 2-methoxy-4-nitroaniline, 
in which Z may be the same or different and is CONR1R2, SO2NR1R2, CONH(CH2)KNR1R2, SO2NH(CH2)KNR1R2, COOH or SO3H (in which each of R1 and R2 is independently a hydrogen atom or an alkyl group, or R1 and R2 together form a cyclic structure, and k is an integer of 1 to 4), s is an integer of 1 or 2, Q may be the same or different and is R3, OR3 or NO2(in which R3 is a hydrogen atom or an alkyl group), and t is an integer of 0 to 2.
According to the present invention, further, there is provided a pigment yellow 74 obtained by coupling a coupler component containing 2-methoxyacetoacetoanilide with a diazo component obtained by diazotizing 2-methoxy-4-nitroaniline and an aniline derivative of the formula (2) in an amount of 0.1 to 10 mol % based on the 2-methoxy-4-nitroaniline, 
wherein Z may be the same or different and is CONR1R2, SO2NR1R2, CONH(CH2)KNR1R2, SO2NH(CH2)KNR1R2, COOH or SO3H (in which each of R1 and R2 is independently a hydrogen atom or an alkyl group, or R1 and R2 together form a cyclic structure, and k is an integer of 1 to 4), s is an integer of 1 or 2, Q may be the same or different and is R3, OR3 or NO2 (in which R3 is a hydrogen atom or an alkyl group), and t is an integer of 0 to 2.
According to the present invention, further, there is provided a printing ink composition comprising the pigment yellow 74 recited the above and a vehicle for a printing ink.
In the present invention, R1 and R2 in an acetoacetoanilide derivative of the formula (1) and an aniline derivative of the formula (2) are each a hydrogen atom or an alkyl group. As the alkyl group, preferred is an alkyl group having 1 to 18 carbon atoms, and an alkyl group having 1 to 4 carbon atoms is more preferred. Further, as a cyclic structure obtained by bonding of R1 and R2, there is a five-membered ring or a six-membered ring. The above cyclic structure may further contain a nitrogen atom or an oxygen atom as a constituent component.
Examples of an amine residue represented by xe2x80x94NR1R2 in the formula (1) and the formula (2) include a methylamino group, an ethylamino group, a stearylamino group, a dimethylamino group, a diethylamino group, a methylaminopropylamino group, a dimethylaminopropylamino group, a diethylaminopropylamino group and a N-aminoethyl-4-pipecolinyl group, while the amine residue shall not be limited to these examples.
Further, R3 in the formula (1) is a hydrogen atom or an alkyl group. As the alkyl group, an alkyl group having 1 to 4 carbon atoms is preferred.
Further, examples of an aniline derivative having a carboxyl group or a sulfonic group include 4-methoxyaniline-2-sulfonic acid, 2,5-dimethoxyaniline-4-sulfonic acid, 2-nitroaniline-4-sulfonic acid and 2-chloro-4-sulfo-5-aminobenzoic acid.
The pigment yellow 74 of the present invention can be produced according to a conventionally-known method. That is, 2-methoxy-4-nitroaniline is diazotized to prepare a diazonium component, on the other hand, the acetoacetoaniline derivative of the formula (1) in an amount of 0.1 to 10 mol %, preferably 1 to 5 mol %, based on 2-methoxyacetoacetoanilide, is added to 2-methoxyacetoacetoanilide to prepare a coupling component, and the diazonium component and the coupling component are coupled according to a general method.
Further, when the aniline derivative of the formula (2) is used as a diazo component, the aniline derivative in an amount of 0.1 to 10 mol %, preferably 1 to 5 mol %, based on 2-methoxy-4-nitroaniline, is added to 2-methoxy-4-nitroaniline, then the resultant mixture is diazotized and coupling is similarly carried out. The coupling reaction is not specially limited, and it may be a batch method carried out under an acidic condition of acetic acid, which is usually called an acid dipping method, or a continuous method in which a diazo solution and a coupling solution are simultaneously added in equal reaction amounts.
The pigment yellow 74 of the present invention in the state of a wet cake is flushed with a vehicle for a printing ink to prepare a printing ink. Otherwise, a powdery pigment of the pigment yellow 74 is kneaded with a vehicle for a printing ink to prepare a printing ink. The pigment for the flushing can be obtained as a wet cake by filtrating and washing a slurry after coupling and compressing it such that a pigment content becomes 26 to 32% by weight. The powdery pigment can be obtained by drying the wet cake and pulverizing the dried wet cake.
When an offset printing ink is produced by using the pigment yellow 74 of the present invention, flushing is carried out with a flusher and, in this case, 180 to 220 parts by weight of an offset printing ink vehicle is added to 100 parts by weight of the wet cake as a dry pigment. The preparation of an ink from the powdery pigment is carried out with a three-roll mill and, in this case, 350 to 450 parts by weight of a vehicle for an offset printing ink is added to 100 parts by weight of the powdery pigment.
The pigment yellow 74 of the present invention can be used as a yellow pigment for an offset printing ink for process ink. An offset printing ink composition is composed of 3 to 35% by weight of the pigment yellow 74 of the present invention, 97 to 45% by weight of a vehicle for an offset printing ink and 0 to 20% by weight of other auxiliary agents (a dryer, a leveling-improving agent or a thickening agent) or an extender pigment. The vehicle for an offset printing ink is generally composed of 20 to 50% by weight of a resin, 0 to 30% by weight of a vegetable oil and 10 to 60% by weight of a solvent. Examples of the resin include a rosin-modified phenol resin, a petroleum resin, an alkyd resin or drying-oil-modified resins of these. Examples of the vegetable oil include linseed oil, tung oil and soybean oil. Examples of the solvent include n-paraffin, isoparaffin, aromatic, naphthene and xcex1-olefin. Further, various known additives for an ink, such as a dryer or a leveling-improving agent, are incorporated to prepare the printing ink composition.
The pigment yellow 74 of the present invention can be used as a yellow pigment for a gravure printing ink for a process ink. A vehicle for a gravure printing ink is generally composed of 10 to 50% by weight of a resin and 30 to 80% by weight of a solvent. Examples of the resin include a gum rosin, a wood rosin, a tall oil rosin, a lime rosin, a rosin ester, a maleic resin, a polyamide resin, a vinyl resin, cellulose nitrate, cellulose acetate, ethyl cellulose, chlorinated rubber, cyclized rubber, an ethylene-vinyl acetate copolymer resin, a polyurethane resin, a polyester resin, an alkyd resin, an acrylic resin, gilsonite, dammar, shellac, mixtures of these, water-soluble resins obtained by rendering any one of the above resins or a mixture of these water-soluble, or an emulsion resin. Examples of the solvent include hydrocarbon, alcohol, ketone, ether alcohol, ether, ester and water.
The pigment yellow 74 of the present invention can be used as a yellow pigment for a color-electrophotographic toner, for water-based and oil-based inkjet recording liquids, and for a resist ink which is used for a color filter for a liquid crystal display and contains a photosensitive resin as a main component.
According to the present invention, there is provided a pigment yellow 74 which is improved in transparency and color strength without impairing its inherent light resistance and clearness.
The present invention will be explained with reference to Examples in detail hereinafter, in which xe2x80x9cpartxe2x80x9d stands for xe2x80x9cpart by weightxe2x80x9d and xe2x80x9c%xe2x80x9d stands for xe2x80x9c% by weightxe2x80x9d unless otherwise specified.